Liquid crystal display device

ABSTRACT

In this display device, an electrode layer for an upper electrode and a lower electrode is formed on an array substrate via a dielectric film, one of the upper electrode and the lower electrode is a pixel electrode, the other thereof is a common electrode, and an opening portion for generating horizontal electric field in a liquid crystal layer is formed in accordance with a shape of the electrode layer in a plan view. A CF substrate has a light-shielding film (BM) including a lateral BM portion. The opening portion has a plurality of slits in an X direction, and an end portion of an outermost slit in a Y direction is concealed by the lateral BM portion overlapped in a Z direction.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/186,822, filed on Jun. 20, 2016, whichapplication is a continuation application of U.S. patent applicationSer. No. 14/033,132, filed on Sep. 20, 2013, issued as U.S. Pat. No.9,383,614 on Jul. 5, 2016, which application claims priority to JapanesePriority Patent Application JP 2012-217725 filed in the Japan PatentOffice on Sep. 28, 2012, the entire content of which is herebyincorporated by reference.

BACKGROUND

The present invention relates to techniques for a display device andelectronic equipment. In particular, the present invention relates to aliquid crystal display device (abbreviated as LCD) which controls liquidcrystal molecules by a horizontal electric field system and the like.

In liquid crystal display devices mounted on various types of electronicequipment, there are an IPS (In-Plane-Switching) system (also referredto as mode), an FFS (Fringe Field Switching) system and the like as thehorizontal electric field system. The horizontal electric field systemis advantageous in such points as a wide viewing angle and an apertureratio (area ratio of a region effective for display in one pixel region)as compared with a vertical electric field system.

As an example of a prior art technique relating to the FFS, there isJapanese Patent Application Laid-Open Publication No. 2008-52161 (PatentDocument 1). The Patent Document 1 (Liquid Crystal Device and ElectronicEquipment) describes a liquid crystal device of an FFS system whichrealizes a bright display with a high aperture ratio without making aconfiguration of the device complicated.

In the IPS mode, a pixel electrode and a common electrode are providedin the same layer, and electric field is mainly generated in a directionparallel to a substrate surface (defined as X and Y directions).Therefore, electric field is hardly formed in a region just above thepixel electrode, so that it is difficult to drive liquid crystalmolecules in the region positioned just above the pixel electrode.

On the other hand, in the FFS mode, a pixel electrode and a commonelectrode are provided so as to be stacked in a direction perpendicularto a substrate surface (defined as Z direction) via a dielectric filminterposed therebetween, and electric field in an oblique direction withrespect to the substrate surface or in a parabolic shape (also referredto as fringe electric field) is generated. Therefore, even the liquidcrystal molecules in a region positioned just above the pixel electrodecan be easily driven. More specifically, an aperture ratio higher thanthat in the IPS mode can be obtained in the FFS mode. Hereinafter, anelectrode positioned on an upper side in the stacked electrodes isreferred to as an upper electrode (first electrode), and an electrode ona lower side is referred to as a lower electrode (second electrode).

SUMMARY

However, even the liquid crystal display device of the FFS systemmentioned above has such a problem as a slow response speed. Note thatthe response speed mentioned here indicates a speed when thetransmittance of liquid crystal is changed between predetermined levelsat the time of applying a voltage to a pixel (including the upper andlower electrodes). More specifically, the response speed is defined bythe time required for the change from an OFF state (for example,transmittance=0) to an ON state (for example, transmittance=1) or by thetime required for the reverse change thereof.

In view of these circumstances, a main object of the present inventionis to provide a display device of a new system which can improve aresponse speed, display quality, and the like as compared with theconventional FFS system or the like in addition to the wide viewingangle and the high aperture ratio.

A representative embodiment of the present invention is a displaydevice, electronic equipment or the like and has the followingconfiguration.

(1) The display device of the present embodiment is a display devicehaving a liquid crystal layer between a first substrate and a secondsubstrate opposed to each other, and it includes: in a case where asubstrate in-plane direction corresponding to a screen is defined asfirst and second directions and a perpendicular direction is defined asa third direction, an electrode layer which has an upper electrode and alower electrode opposed to each other and in which an opening portionhaving a plurality of slits extending in the first direction is formedin the upper electrode or the lower electrode; and a firstlight-shielding film portion extending in the first direction andprovided in the first or second substrate. The liquid crystal layer isprovided on the electrode layer and liquid crystal molecules inneighboring regions on one side and the other side opposed to each otherin a width direction of the slits of the opening portion are rotated indirections opposite to each other to be oriented. In the openingportion, for each pixel, at least part of an end portion of at least oneoutermost slit of outermost slits in the second direction is concealedby the first light-shielding film portion overlapped in the thirddirection.

In particular, the first substrate has the electrode layer and a firstalignment film positioned between the electrode layer and the liquidcrystal layer. The second substrate has a second alignment film betweenthe second substrate and the liquid crystal layer, the first alignmentfilm is subjected to rubbing process in a first rubbing direction whichis approximately parallel to the first direction, the second alignmentfilm is subjected to rubbing process in a second rubbing direction whichis a direction opposite to the first rubbing direction of the firstalignment film, and long axes of liquid crystal molecules are aligned inthe first rubbing direction as an initial orientation state of liquidcrystal in the liquid crystal layer.

In particular, the width of the first light-shielding film portion inthe second direction is equal to or more than a width (H) of apredetermined distance ranging from a line of an end portion of theoutermost slit of the opening portion to the outside. In other words,the width of the first light-shielding film portion in the seconddirection has a size capable of concealing at least a region of thewidth (H) of the predetermined distance.

In particular, the first substrate has a first electrode line extendingin the first direction and a switching element connected to the firstelectrode line, which are components constituting the pixel, the firstlight-shielding film portion is disposed so as to overlap the firstelectrode line and the switching element, and the width of the firstlight-shielding film portion in the second direction is a width whichconceals the first electrode line and the switching element.

(Configuration A) In particular, the upper electrode is a commonelectrode having an opening for each pixel, the lower electrode is apixel electrode having an electrode portion for each pixel, and a regionof the opening of the upper electrode constitutes the opening portion ina plan view.

(Configuration B) In particular, the upper electrode is a pixelelectrode having an electrode portion for each pixel, the lowerelectrode is a common electrode, and a region positioned outside theupper electrode constitutes the opening portion in a plan view.

(Configuration α) In particular, the opening portion has, for eachpixel, a communication opening portion extending in the second directionand a plurality of slits connected to both sides of the communicationopening portion and extending in the first direction. A plurality offirst slits extending in the first direction are arranged on one side ofthe communication opening portion in the second direction, and aplurality of second slits extending in the first direction are arrangedon the other side thereof in the second direction. One end of a longside of the slit constitutes a corner portion closed by the upperelectrode and the other end thereof constitutes a corner portion openedto the communication opening portion. The plurality of slits on bothsides of the communication opening portion are alternately arranged sothat positions thereof are shifted in the second direction. A long sideof the first slit connected to one side of the communication openingportion and a long side of the second slit connected to the other sidethereof are aligned on a line in the first direction.

(Configuration β) In particular, the opening portion has, for eachpixel, a communication opening portion extending in the second directionand a plurality of slits connected to one side of the communicationopening portion and extending in the first direction. The plurality ofslits extending in the first direction are arranged in the seconddirection on one side of the communication opening portion. One end of along side of the slit constitutes a corner portion closed by the upperelectrode and the other end thereof constitutes a corner portion openedto the communication opening portion.

(Shape a) In particular, the upper electrode has a plurality ofprojecting portions for constituting the plurality of slits, and theslits and the projecting portions are trapezoids which are long in thefirst direction and have an upper side on a pixel-inner side.

(Shape b) In particular, the upper electrode has a plurality ofprojecting portions for constituting the plurality of slits, and theslits and the projecting portions are rectangles which are long in thefirst direction.

(2) In particular, as a panel configuration, the first substrate has thefirst electrode line parallel to the first direction, a second electrodeline parallel to the second direction, and a switching element connectedto the first electrode line and the second electrode line for eachpixel, and a pixel electrode is connected to the switching element. Inthe second substrate, the light-shielding film has a firstlight-shielding film portion extending in the first direction and asecond light-shielding film portion extending in the second direction.The first light-shielding film portion overlaps the first electrode lineand the switching element, and the second light-shielding film portionoverlaps the second electrode line. Also, the width of the firstlight-shielding film portion is larger than a width of the secondlight-shielding film portion.

(3) The display device includes: a panel with the configurationdescribed above; a first driver connected to a first electrode line ofthe panel to drive it; a second driver connected to a second electrodeline of the panel to drive it; a third driver connected to an upperelectrode and a lower electrode of the panel to drive them; and acontroller which controls driving of the first to third drivers.

(4) Electronic equipment of the present invention includes the displaydevice described above; a control unit which performs display controlprocess to the display device; and a storage unit which stores displaydata provided to the display device.

According to the representative embodiment of the present invention, itis possible to provide a display device of a new system (high-speedhorizontal electric field mode) which can improve the response speed,the display quality, and the like as compared with the conventional FFSsystem or the like in addition to the wide viewing angle and the highaperture ratio. The response speed, the brightness, and the orientationstability in pixels can be improved, and the display quality can beimproved by uniformizing the pixel characteristics.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a block configuration of a display deviceand electronic equipment according to an embodiment of the presentinvention;

FIG. 2 is a diagram showing a schematic structure of a cross section ofpixels of a liquid crystal panel of the display device of the presentembodiment;

FIG. 3A is a diagram showing shapes of opening portions and electrodesof a pixel (configuration β) in the case of longitudinal slits;

FIG. 3B is a diagram showing shapes of opening portions and electrodesof a pixel (configuration β) in the case of lateral slits (presentembodiment);

FIG. 4A is a diagram showing shapes of opening portions and electrodesof a pixel (configuration α) in the case of longitudinal slits;

FIG. 4B is a diagram showing shapes of opening portions and electrodesof a pixel (configuration α) in the case of lateral slits (presentembodiment);

FIG. 5 is a diagram for describing a liquid crystal orientation and thelike in this system (FIG. 4B);

FIG. 6A is a partially-enlarged diagram of FIG. 5 for describing liquidcrystal orientation and the like at the time of voltage-OFF;

FIG. 6B is a partially-enlarged diagram of FIG. 5 for describing liquidcrystal orientation and the like at the time of voltage-ON;

FIG. 7A is a diagram showing a cross section taken along line A-A′ ofFIG. 5 for describing liquid crystal orientation at the time ofvoltage-OFF;

FIG. 7B is a diagram showing a cross section taken along line A-A′ ofFIG. 5 for describing liquid crystal orientation at the time ofvoltage-ON;

FIG. 8 is a diagram showing a planar configuration example of pixels,BM, and the like of a liquid crystal panel of the present embodiment;

FIG. 9 is a diagram collectively showing configuration examples of upperand lower electrodes in the present embodiment;

FIG. 10 is a diagram showing a planar structure of pixels of a displaydevice (liquid crystal panel) of a first embodiment;

FIG. 11 is a diagram showing a cross-sectional structure of pixels ofthe display device (liquid crystal panel) of the first embodiment;

FIG. 12 is a diagram showing a first light-shielding configurationexample in the first embodiment;

FIG. 13 is a diagram showing a second light-shielding configurationexample in the first embodiment;

FIG. 14 is a diagram showing a third light-shielding configurationexample in the first embodiment;

FIG. 15 is a diagram showing the region near a slit end of a pixel andthe like in the first embodiment;

FIG. 16 is a diagram showing a planar structure of pixels of a displaydevice (liquid crystal panel) of a second embodiment;

FIG. 17 is a diagram showing a cross-sectional structure of pixels ofthe display device (liquid crystal panel) of the second embodiment;

FIG. 18 is a diagram showing a light-shielding configuration example inthe second embodiment;

FIG. 19 is a diagram showing the region near a slit end of a pixel andthe like in the second embodiment;

FIG. 20 is a diagram showing a pixel configuration example forsimulation regarding a first characteristic (light shielding width);

FIG. 21 is a diagram showing an in-plane luminance distribution of thesimulation result regarding the first characteristic;

FIG. 22 is a diagram showing a cross-sectional brightness distributionof the simulation result regarding the first characteristic;

FIG. 23 is a partially-enlarged diagram showing an opening portionregarding the second to fourth characteristics;

FIG. 24 is a graph showing the simulation result regarding the secondcharacteristic (slit pitch);

FIG. 25 is a table showing the simulation result regarding the thirdcharacteristic (comb tooth angle);

FIG. 26 is a graph showing the simulation result regarding the fourthcharacteristic (longitudinal slit width);

FIG. 27A is an explanatory diagram regarding a fifth characteristic(retardation R=Δnd), showing a cell thickness d and the like;

FIG. 27B is an explanatory diagram regarding the fifth characteristic(retardation R=Δnd), showing a function between the cell thickness d andthe retardation R;

FIG. 28 is a graph showing brightness in accordance with R of thesimulation result regarding the fifth characteristic;

FIG. 29 is a graph of the simulation result regarding a sixthcharacteristic (elastic constant of liquid crystal); and

FIG. 30 is a diagram collectively showing the preferred conditions ofcharacteristics for the display device of the present embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Note that the samecomponents are denoted by the same reference symbols throughout thedrawings for describing the embodiments, and the repetitive descriptionthereof will be omitted. Also, for making the features of the inventioneasily understood, the hatching of the cross section is arbitrarilyomitted and main components are highlighted. Furthermore, the dimensionsand the scale are sometimes different from those in actual cases.

<Outline>

In the embodiments, the case of application to a liquid crystal displaydevice (LCD) which can display a color moving image on a screen andelectronic equipment on which the LCD is mounted will be described. InFIG. 1 to FIG. 9, a basic embodiment including premise will bedescribed. Based on the basic embodiment, a first embodiment will bedescribed in FIG. 10 to FIG. 15, and a second embodiment will bedescribed in FIG. 16 to FIG. 19. In FIG. 20 to FIG. 30, preferableconditions for characteristics will be described.

A liquid crystal panel 1 of the present embodiment basically adopts ahorizontal electric field mode as shown in FIG. 2, but it adopts a newsystem (high-speed horizontal electric field mode different from theconventional FFS system) obtained by applying a rubbing process of ananti-parallel orientation in a direction parallel to an extensiondirection (X) of a slit 50A as shown in FIG. 4B, FIG. 10, FIG. 12, andthe like. The details of the high-speed horizontal electric field modewill be described later. The liquid crystal panel 1 of the embodiment isstructured to have an opening portion (also referred to as slit) 50Aformed by upper and lower electrodes (31, 32) and adapted to thehigh-speed horizontal electric field mode. The opening portion 50A isformed to have a comb-like shape including a plurality of lateral(X-directional) slits S. Further, in the liquid crystal panel 1 of thepresent embodiment, an end portion (A1 and the like) of the openingportion (slit) 50A of a pixel in a longitudinal (Y) direction isconcealed by a wider one (lateral BM portion 22A) of light shieldingfilms (BM) 22. This is because the high-speed response expected in theabove-described high-speed horizontal electric field mode cannot beachieved and a response speed approximately equal to that of theconventional FFS mode is merely obtained. More specifically, byconcealing the end portion (A1 and the like) of the slit 50A by theBM22, the characteristic (second characteristic in which the responsespeed is approximately equal to that of the conventional FFS system atthe end portion of the slit 50A) of the region of the end portion of thepixel (indicated by Q2 in FIG. 4B) is suppressed to uniformize theoverall characteristic to the characteristic (first characteristic inwhich a high response speed is achieved by the high-speed horizontalelectric field mode) of the region (Q1) inside the pixel.

[Electronic Equipment/Liquid Crystal Display Device]

FIG. 1 shows a block configuration of a liquid crystal display device100 which is a display device of the present embodiment and electronicequipment 200 on which the liquid crystal display device 100 is mounted.The electronic equipment 200 includes the liquid crystal display device(in other words, LCD module) 100, a control unit 201, a storage unit202, an input unit 203, an output unit 204, a display I/F (interface)unit 205, and the like. The control unit is composed of, for example,CPU, ROM, RAM, and a program running on these members. For example, theCPU controls the electronic equipment 200 by computing process inaccordance with a program loaded from the ROM to the RAM. The storageunit 202 is composed of a primary memory, a secondary memory, and datainformation including video data and the like stored therein. The inputunit 203 is composed of an input device such as a button and an I/Fprocessing unit thereof. The output unit 204 is composed of an outputdevice other than the display device and an I/F processing unit thereof.The display I/F unit 205 connects the liquid crystal display device 100to perform I/F processing thereof. A communication I/F unit, a powersource unit and the like (not shown) are also provided.

The liquid crystal display device (LCD module) 100 is configured to havea liquid crystal panel 1, an LCD driver 101 (in other words, an LCDcontroller) which performs main drive control, and respective drivers(gate driver 111, data driver 112, upper and lower electrode driver 113)which drive respective signal lines of the liquid crystal panel 1. Forexample, the respective drivers are mounted by the circuits on aflexible printed circuit board on which an IC chip is formed or a glasssubstrate of the liquid crystal panel 1. Note that the respectivedrivers may be properly provided in an integrated manner or in aseparated manner.

The control unit receives a video signal from outside or produces a videsignal therein. A video signal or control instruction information is fedfrom the control unit to the LCD driver 101 via the display I/F unit205. The LCD driver 101 feeds video/image data and control signals suchas a timing signal to respective drivers (111 to 113) to control them.The gate driver 111 feeds scanning signals to a gate line (GL) group ofthe liquid crystal panel 1 in accordance with the control. The datadriver 112 feeds a data signal to a data line (GL) group of the liquidcrystal panel 1 in accordance with the control. The upper and lowerelectrode driver 113 feeds corresponding voltage signals (namely, apixel voltage to a pixel electrode PIX and a common voltage to a commonelectrode COM) to an upper electrode 31 and a lower electrode 32 (FIG.2) of the liquid crystal panel 1 in accordance with the control.

As examples of the electronic equipment 200, various types of devicessuch as a television set (in other words, liquid crystal TV device), adisplay for PC, a digital camera/video camera, a laptop PC, a portablephone such as a smart phone, a portable terminal such as a tablet, and adisplay for car navigation system can be applied. For example, in thecase of the liquid crystal TV device or the display for PC, a filterglass or the like is added to a front face of the LCD module 100 andthey are held by a casing. For example, in the case of the digitalcamera or the video camera, a display unit such as a finder/monitor isconstituted by the LCD module 100. For example, in the case of thelaptop PC, a display screen is constituted by the LCD module 100. Forexample, in the case of the portable phone, the display screen isconstituted by the LCD module 100.

[Liquid Crystal Panel—Cross Section]

FIG. 2 schematically shows a cross-sectional configuration of a pixeltaken along a Y-Z plane as a basic structure of the liquid crystal panel1 shown in FIG. 1. The liquid crystal panel 1 is roughly composed of anarray substrate 10 which is a first substrate, a CF substrate 20 (alsoreferred to as opposed substrate) which is a second substrate, and aliquid crystal layer 30 sandwiched and sealed therebetween. Note thatFIG. 2 shows a schematic configuration, in which an insulating film, analignment film, a polarizing plate, a backlight, and other knownelements are not illustrated.

The array substrate 10 is a substrate assembly including a structure ona back face side with respect to the line of sight and a glass substrate11. In the Z direction, a lower electrode 32, a dielectric film 33 andan upper electrode 31 are stacked on the glass substrate 11.Specifically, a gate line, a TFT portion, and the like are alsoprovided, and they are described later. As illustrated, there areoverlaps of electrode portions (here, the upper electrode 31) on theopposed faces of the upper electrode 31 and the lower electrode 32, andan opening portion (50 in FIG. 3, FIG. 4, and the like) including slitsS is formed in accordance with the shape thereof in a plan view (X-Y).On the electrode layer of the upper and lower electrodes (31, 32)including the opening portion, the orientation of liquid crystal of theliquid crystal layer 30 is controlled in a substrate in-plane direction(X-Y) in this system (namely, a horizontal electric field mode).

One of the upper and lower electrodes (31, 32) is a pixel electrode(PIX), and the other is a common electrode (COM). The upper and lowerelectrodes (31, 32) constitute an electrode portion for forming thefringe electric field in the liquid crystal layer 30. As theconfiguration examples of these combinations, various combinations arepossible and they are collectively shown in FIG. 9 described later. Thecommon electrode COM is basically formed as a solid layer over aplurality of pixel regions (for example, the screen), and it iscontrolled to a common potential by the application of a common voltageregardless of respective pixels. The pixel electrode PIX is constitutedof a rectangular layer corresponding to each pixel, and a voltagecorresponding to each pixel is applied thereto, so that it is controlledto a potential corresponding to each pixel. The upper and lowerelectrodes (31, 32) are made of a material having visible-lighttransmissivity and electrical conductivity such as ITO(Indium-Tin-Oxide) (in other words, transparent electrode). In the casewhere the common electrode COM is constituted of a plurality of blocksor the like instead of the solid layer, these blocks are connected bycommon electrode lines.

The CF substrate 20 is a substrate assembly including a structure on afront face side with respect to the line of sight and a glass substrate21. For example, layers of BM 22, CF 23 and the like are formed on aninner face side (indicating a side near the liquid crystal layer 30) onthe glass substrate 21 in the Z direction. FIG. 2 shows an example wherethe BM 22 and the CF 23 are formed in the same layer, but they may beformed in difference layers. An overcoat layer having a function as aplanarization/protection layer (not shown) and the like may be providedon (an inner face side of) the BM 22 and the CF 23. Further, anantistatic layer or the like may be provided on the front face side ofthe CF substrate 20 other than the polarization plate.

The BM 22 is a light-shielding film (also referred to as black film),which reduces crosstalk between pixels and is constituted of alight-shielding (light-absorptive or low light transmissive) materialsuch as a metal material including Cr or stacked color filters ofrespective colors. The BM 22 is formed in a grid-like shape for definingpixels. The CF 23 is a color filter arranged so as to correspond to apixel arrangement, and it is composed of respective layers of threecolors of, for example, R, G, and B (see FIG. 8 described later). Notethat, in the present embodiment, the BM 22 is formed on the CF substrate20 side, but the BM 22 may be formed on the array substrate 10 side(above the electrode layers of the upper and lower electrodes (31, 32))as another aspect.

The liquid crystal layer 30 is a layer in which nematic liquid crystalis sealed between the upper and lower substrates (10, 20) via analignment film. The upper and lower substrates (10, 20) are connected ina frame edge portion of the liquid crystal panel 1 by a sealing materialand liquid crystal is sealed inside a space therebetween. In the liquidcrystal layer 30, a predetermined rubbing process (described later) isapplied to the alignment film, so that the liquid crystal is put into apredetermined initial orientation state.

By applying a voltage from a driver side (FIG. 1) to the upper and lowerelectrodes (31, 32), a predetermined potential difference correspondingto modulation of transmittance of liquid crystal of a pixel is impartedbetween the upper and lower electrodes (31, 32) via the dielectric film33. Fringe electric field is generated in the vicinity of the openingportion (50) of the pixel in the liquid crystal layer 30 by thepotential difference, so that the orientation state is controlled so asto mainly rotate liquid crystal molecules in the substrate in-planedirection (X, Y directions).

Polarization plate is disposed on each of the back face side of thearray substrate 10 and the front face side of the CF substrate 20, sothat a polarization state of transmitted light is controlled.Transmission axes of the upper and lower polarization plates are put inan orthogonal relation (normally-black configuration), and one of themis the same as the rubbing direction (described later).

A backlight or the like is disposed on the back face side of the arraysubstrate 10, and a backlight illumination state or the like iscontrolled in accordance with LCD control from a driver for backlightcontrol (not shown). By controlling the transmission and polarizationlights in accordance with the pixel states on the liquid crystal panel 1based on the emitted light from the backlight, an image is formed on ascreen on the front face side.

[Rubbing Direction]

The liquid crystal in the liquid crystal layer 30 is subjected torubbing process in a predetermined rubbing direction on upper and loweralignment films (first and second alignment films) of the liquid crystallayer 30 so as to have a predetermined initial orientation correspondingto the high-speed horizontal electric field mode. On the first alignmentfilm between the electrode layers (31, 32) on the array substrate 10side and the liquid crystal layer 30, rubbing process is performed in afirst rubbing direction which is a direction approximately parallel tothe X direction in which the slits S or the like extend (Rub in FIG. 3Band FIG. 4B, a direction from the left to the right of the drawing). Onthe second alignment film between the CF substrate 20 and the liquidcrystal layer 30, rubbing process is performed in a second rubbingdirection which is a direction opposite to the first rubbing directionof the first alignment film. The high-speed horizontal electric fieldmode is established by the anti-parallel orientation. In this manner,long axes of the liquid crystal molecules are aligned along the firstrubbing direction (Rub) as an initial orientation state of liquidcrystal in the liquid crystal layer 30.

The liquid crystal in the liquid crystal layer 30 is made of, forexample, nematic liquid crystal having negative dielectric constantanisotropy. In this case, the rubbing direction (Rub) is set parallel tothe X direction in which the slits S or the like extend as describedabove. Note that, in the case where nematic liquid crystal havingpositive dielectric constant anisotropy is used, the rubbing direction(Rub) is set parallel to the orthogonal direction (Y). Theabove-described rubbing direction (Rub) is not limited to a directioncompletely parallel to the X direction in which the slits S or the likeextend, and an angle to a certain extent (for example, one degree) isallowed.

[Manufacturing Method]

A manufacturing method of a liquid crystal panel 1 is, for example, thefollowing processes, and the case of a configuration A shown in FIG. 9will be described. On the array substrate 10 side, layers for gatelines, data lines, a TFT portion, and the like are formed on the glasssubstrate 11. An insulating film having a function as a planarizationlayer is formed thereon. The insulating film is made of a material suchas polyimide or silicon oxide. The lower electrode 32 (pixel electrodePIX) is formed on the insulating film by patterning such asphoto-etching of ITO. The thickness of the pixel electrode PIX is, forexample, 500 to 1500 angstroms. The dielectric film 33 is formed over awhole surface of the lower electrode 32 as a solid layer. The dielectricfilm 33 has insulation properties and protection properties, is made ofa material such as silicon nitride or silicon oxide, and is formed by aplasma CVD method or the like. The thickness of the dielectric film 33is, for example, 100 to 1000 angstroms. The upper electrode 31 (commonelectrode COM) made of ITO is formed on the dielectric film 33. Forexample, the common electrode COM constituted of a solid layer havingslits (opening portion) is formed by sputtering, etching, or the like.The thickness of the common electrode COM is, for example, 100 to 1000angstroms. The first alignment film subjected to the rubbing process ina predetermined rubbing direction is formed on the upper electrode 31.The alignment film is constituted of the film obtained by performingrubbing process to a polymer material such as polyimide.

On the CF substrate 20 side, the layers of CF 23, BM 22 and the like areformed on the glass substrate 21, an overcoat layer or the like isformed thereon, and the second alignment film obtained by performing therubbing process in a predetermined direction is formed thereon. Theliquid crystal layer 30 is formed by causing the array substrate 10 andthe CF substrate 20 to face each other, injecting liquid crystaltherebetween, and then connecting the substrates 10 and 20 in a frameedge portion by a sealing material. A polarization plate, a backlight,and the like are attached to the back face side of the liquid crystalpanel 1 and a polarization plate and the like are attached to the frontface side thereof. Respective drivers (FIG. 1) are connected toelectrode ends of the frame edge portion of the liquid crystal panel 1,thereby constituting the liquid crystal display device 100.

[Pixel (Configuration B, Configuration β)]

FIGS. 3A and 3B show the configurations of electrodes, an openingportion, and the like of a pixel on an X-Y plane in the case of aconfiguration B and a configuration β shown in FIG. 9, andcharacteristics of a slit end portion or the like will be described. Theconfiguration B shows a case where the upper electrode 31 is a pixelelectrode PIX and the lower electrode 32 is a common electrode COM, andthe configuration β shows a case of one-side comb-like shape. FIG. 3Ashows a case in which longitudinal slits existing in the conventionalFFS system are provided, and FIG. 3B shows a case in which lateral slits(S) of the present embodiment are provided. Since the configuration β issimpler in shape than the configuration α, the configuration β isdescribed first.

In FIG. 3A, a reference numeral 401 denotes an electrode portion of anupper electrode (pixel electrode PIX). Since a lower electrode (commonelectrode COM) facing the upper electrode in the Z direction is a solidlayer, the illustration thereof is omitted. A reference numeral 402denotes a schematic pixel region corresponding to the region of 401. Areference numeral 400 denotes a region of a slit (in other words,opening portion) formed by the upper and lower electrodes, and itcorresponds to a region outside the electrode portion 401. In thisregion, only a portion of the lower electrode (COM) is present, and aportion of the upper electrode (PIX) does not overlap the lowerelectrode. Note that the shape of the pixel electrode, the number ofcomb teeth and the like can be adjusted in accordance with the pixeldesign. In FIG. 3A, a laterally-long shape is shown for easyunderstanding in comparison with FIG. 3B, but a longitudinally-longshape is adopted in the case where a longitudinally-long pixel isformed.

A reference sign S denotes an individual slit in a longitudinal (Y)direction (in other words, opening, clearance, or the like). Note thatthe reference numeral 400 denotes the slits (opening portion) on a wholepixel, which includes a plurality of individual slits S. Reference signsS1 and S2 denote a left-side outermost slit and a right-side outermostslit in the X direction of a plurality of slits S having the same shape.Each slit S has one end (upper side in FIG. 3A) closed by the electrodeportion 401 and the other end (lower side in FIG. 3B) opened andconnected to adjacent slits. Reference sings E1, E2, and E3 denoteprojecting portions (in other words, comb teeth) of the electrodeportion 401 extending in the Y direction. In this case, each comb toothhas a rectangular shape. The slit S is formed by a pair of the combteeth adjacent to each other in the X direction. A reference sign Ewdenotes a wider projecting portion of the electrode portion 401, inother words, a pixel electrode end portion. A reference sign a0 denotesan end line of the pixel (401, Ew). A reference sign a1 denotes a lineof a slit end SE of the slit end portion (end portion of the outermostslit S1). The same is true of reference signs S2 and b1 (SE).

A reference sign R1 denotes a pixel-inside region having a boundary inthe vicinity of a1 (SE) and b1 (SE), in which the above-described firstcharacteristic is secured. A reference sign R2 denotes a pixel endportion region positioned outside the region R1 (SE), which is a regionhaving the above-described second characteristic of relatively slowresponse speed which is different from the first characteristic of R1.

In FIG. 3A, the rubbing direction (Rub) on the array substrate side is adirection toward a closed end side of the slit S in the longitudinal (Y)direction (from bottom to top in FIG. 3A).

FIG. 3B approximately corresponds to a configuration in which FIG. 3Ahas been rotated in a clockwise direction by 90° (details of the pixelelectrode and the like are omitted). A reference numeral 50B denotes aregion of an opening portion (slit) in a whole pixel formed by the upperand lower electrodes (401, 402) in the case of the configuration B. Areference numeral 401 corresponds to the upper electrode 31 (PIX) and areference numeral 402 corresponds to the schematic pixel region of thelower electrode 32 (COM). Also, a reference numeral 403 denotes anexample of a connection portion with a TFT portion 43 (contact receiver44 connected thereto) described later. A reference sign L0 denotes alength of the slit S. In the case where the configuration of the upperand lower electrodes (31, 32) and the opening portion 50B shown in FIG.3B is applied to an LCD, the region of R1 defined by the slit ends SEserving as boundaries is caused to have the above-described firstcharacteristic with a high-speed responsiveness corresponding to the newsystem (high-speed horizontal electric field mode) of the presentembodiment. However, the region of R2 has the above-described secondcharacteristic with relatively slow responsiveness or the like. Indetail, the region of R2 is slower in response speed at the time ofapplying a voltage than the region of R1, and R2 is different from R1 inluminance curve, orientation stability, and the like. Since the regionof R1 and the region of R2 are different in initial orientation statefrom each other, there is a possibility that distortion on displayoccurs due to orientation abnormality in the region of R2.

Therefore, in the present embodiment (second embodiment describedlater), the region of R2 is a candidate region to be concealed byoverlapping it with BM 22 (lateral BM portion 22A). More specifically,the pixel configuration in which the region of R2 is concealed by thelateral BM portion 22A with a large width is adopted. In this manner,the new system (high-speed horizontal electric field mode) in whichcharacteristics such as a response speed are improved and uniformized inthe pixel can be realized. The luminance curve and the orientationstability can be also uniformized in addition to the responsiveness, sothat the display quality can be improved.

As shown in FIG. 3B, by adopting the configuration of the openingportion 50B having the slits S extending in the lateral (X) direction,light shielding for the pixel end portion region (R2) can be easily madeby the lateral BM portion 22A with a large width as described later(FIG. 8), and an efficient pixel configuration can be realized. Forexample, it is possible to take a wide region effective for display of apixel. By way of comparison, in the case where the regions (R2) at theleft and right end portions of the pixel are concealed by the BM 22(longitudinal BM portion 22B) in FIG. 3A, there is a demerit that it isimpossible to take a wide region effective for display of the pixel andan inefficient pixel configuration is formed.

As described above, in the case where the slit end portionscorresponding to the regions of R2 on both ends of the pixel arepositioned between pixels, the opening portion 50B having the slit Sextending in the X direction is disposed in conformity with theconfiguration of the lateral BM portion 22A as shown in FIG. 3B so thatthe difference in the characteristics of R1 and R2 (for example, leakagelight caused due to the difference in the characteristics) can beefficiently hidden (FIG. 16 described later and the like).

[Pixel (Configuration A, Configuration α)]

FIGS. 4A and 4B show the configurations of electrodes, an openingportion, and the like of a pixel on an X-Y plane in the case of aconfiguration A and a configuration α shown in FIG. 9, andcharacteristics of a slit end portion or the like will be described. Theconfiguration A shows a case where the upper electrode 31 is a commonelectrode COM and the lower electrode 32 is a pixel electrode PIX, andthe configuration α shows a case of both-side comb-like shape. FIG. 4Ashows a case provided with longitudinal slits, and FIG. 4B shows a caseof the present embodiment where lateral slits (S) are provided.

In FIG. 4A, a reference numeral 501 denotes an electrode portion of theupper electrode (COM). A reference numeral 502 denotes a rectangularregion of the lower electrode (PIX), which corresponds to a schematicpixel region. A reference numeral 500 denotes a region of an openingportion (slit) of a whole pixel formed by the upper and lower electrodes(501, 502), and it corresponds to a region outside the electrode portion501. In this region, only a portion of the lower electrode (PIX) ispresent, and a portion of the upper electrode (COM) does not overlap thelower electrode. A reference numeral 503 (Ka) denotes a projectingportion (comb tooth) of the electrode portion 501 extending long in anupward direction, and a reference numeral 504 (Kb) denotes a projectingportion (comb tooth) extending long in a downward direction. In thiscase, each comb tooth has a rectangular shape. An individual slit (Sa,Sb) is formed by a pair of comb teeth adjacent to each other in the Xdirection. A reference numeral 508 denotes an electrode portionextending in the lateral (X) direction, which connects one ends of aplurality of projecting portions (Ka, Kb). In this manner, a both-sidecomb-like shape where comb teeth (Ka, Kb) alternately extend upward anddownward from an axis (508) extending in the X direction is formed.

A reference numeral 505 (Sa) denotes an individual slit of the openingportion 500 extending long upward in the longitudinal (Y) direction, anda reference numeral 506 (Sb) denotes an individual slit of the openingportion 500 extending long downward in the longitudinal (Y) direction. Areference numeral 507 denotes a slit (also referred to as communicationopening portion) extending in the lateral (X) direction, and it connectsone ends of a plurality of slits (Sa, Sb). One end of each slit (Sa, Sb)is closed by the electrode portion 501, and the other end thereof isopened to communicate with the communication opening portion 507. Inthis manner, the both-side comb-like shape where slits (Sa, Sb)alternately extend upward and downward from an axis (507) extending inthe X direction is formed.

A reference sign A1 denotes regions of left and right end portions ofthe opening portion 500 of a pixel in the X direction, and the endportion A1 demarcates the boundary between the regions having differentcharacteristics as described above. In FIG. 4A, the rubbing direction(Rub) on the array substrate side is a direction parallel to the slitextending in the longitudinal (Y) direction (downward direction in FIG.4A).

FIG. 4B approximately corresponds to a configuration where FIG. 4A isrotated in a counterclockwise direction by 90° (details of the pixelelectrode and the like are omitted). A reference numeral 50A shows aregion of an opening portion (slit) of a whole pixel formed by the upperand lower electrodes (31 (COM), 32 (PIX)) in the case of theconfiguration A, and it corresponds to a region outside the upperelectrode 31. In this region, only a portion of the lower electrode 32(PIX) is present, and a portion of the upper electrode 31 (COM) does notoverlap the lower electrode. Note that the opening portion 50 (50A, 50B)does not mean a region of the pixel region effective for display butindicates a region where only the lower electrode 32 exists due toabsence of the upper electrode 31 regarding the overlapping of the upperand lower electrodes (31, 32) in the plan view (X-Y). A referencenumeral 53 (Ka) denotes a projecting portion (comb tooth) of theelectrode (31) extending long in a leftward direction, and a referencenumeral 54 (Kb) denotes a projecting portion (comb tooth) extending longin a rightward direction. An individual slit S (Sa, Sb) is formed by apair of comb teeth adjacent to each other in the Y direction. Areference numeral 58 denotes the electrode portion of the upperelectrode 31 extending in the longitudinal (Y) direction, which connectsone ends of the plurality of projecting portions (Ka, Kb). Morespecifically, the upper electrode 31 (COM) has a both-side comb-likeshape where the comb teeth (Ka, Kb) alternately project leftward andrightward from the axis (58) extending in the Y direction.

A reference numeral 55 (Sa) denotes an individual slit of the openingportion 50A extending long leftward in the X direction, and a referencenumeral 56 (Sb) denotes an individual slit extending long rightward inthe X direction. A reference numeral 57 denotes a slit (also referred toas communication opening portion) extending in the longitudinal (Y)direction, which connects one ends of a plurality of slits S (Sa, Sb) toform a continuous opening. One end portion of each slit S is closed bythe electrode portion (31), and the other end portion thereof is openedto communicate with the communication opening portion 57.

In the opening portion 50A, a plurality of slits S disposed in a row inthe Y direction and having the same X-directional positions have thesame shape, and left and right end positions thereof are aligned,respectively, and they are arranged at constant pitches in the Ydirection. A group of slits S in rows adjacent in the X direction formsa both-side comb-like shape where the slits S are alternately arrangedleftward and rightward from the communication opening portion(longitudinal slit) 57 extending in the Y direction so as to be shiftedin the Y direction. The length of the shift corresponds to ½ of thepitch of the slits S in the Y direction (see FIG. 23 described later).The both-side comb-like shape having alternately arranged teeth can alsobe referred to as a structure where the slits S and projecting portions(electrode portion) are arranged in a staggered manner.

A slit end SE indicates an outer side (line) of a slit positionedoutermost in the Y direction (referred to as outermost slit) in theconfiguration of the opening (slits) 50 formed by the upper and lowerelectrodes (31, 32) of the pixel. In this case, the slit end SEcorresponds to a side of the rectangle of the lower electrode 32 (PIX).An end portion (also referred to as “slit end portion”) A1 is a regionof upper and lower end portions in the Y direction of the openingportion 50A of the pixel, and it is a region including the line of theslit end SE as a center.

In FIG. 4B, the rubbing direction (Rub) on the array substrate 10 sideis a direction parallel to the X direction (in a left-to-right directionin the drawing) so as to correspond to the structure of the slit S inthe lateral (X) direction. Note that a reference sign L0 indicates atotal length of the slits in the X direction of the opening portion 50A(including the widths of Sa, Sb, and 57). Reference signs L1 and L2 arelengths of the left and right slits (Sa, Sb), respectively.

In the case where the configuration of the upper and lower electrodes(31, 32) and the opening portion 50A shown in FIG. 4B is applied to theLCD, the characteristics such as the response speed are differentbetween the pixel-inside region Q1 and a pixel end portion region Q2demarcated by the boundary of A1 (SE) as described above. The region ofQ1 is caused to have the above-described first characteristic with ahigh-speed responsiveness corresponding to the new system (thehigh-speed horizontal electric field mode). However, the region of Q2 iscaused to have the above-described second characteristic (secondcharacteristic with the response speed approximately equal to that ofthe conventional FFS system at an end portion of the slit). One of thereasons is because of the difference in shape and presence/absence ofthe upper and lower electrodes (31, 32). In detail, the region of Q2 isslower in response speed at the time of applying a voltage than theregion of Q1, and Q2 is different from Q1 in luminance curve,orientation stability, and the like. Since the region of Q1 and theregion of Q2 are different in initial orientation state from each other,there is a possibility that distortion on display occurs due toorientation abnormality in the region Q2.

Therefore, in the configuration of the present embodiment (firstembodiment described later), the region Q2 demarcated by the boundary ofthe end portion A1 (slit end SE) of the pixel in the Y direction isoverlapped with the BM 22 (particularly, lateral BM portion 22A)described later (FIG. 8 and others) disposed thereabove in the Zdirection. In this manner, the region of Q2 is concealed to hide thesecond characteristic. More specifically, the pixel configuration wherethe second characteristic of the region of Q2 is hidden by the lateralBM portion 22A with a large width is adopted. As a result, thecharacteristics (the response speed, the luminance curve, theorientation stability, and the like) of the region of Q2 can besuppressed at each pixel, so that the overall characteristics can beuniformized to the characteristic of the region of Q1, and the displayquality can be improved.

As shown in FIG. 4B, by adopting the configuration of the openingportion 50A having the slits S extending in the lateral (X) direction,light shielding for the region (Q2) of the end portion (A1) can beeasily made by the lateral BM portion 22A with a large width asdescribed later (FIG. 8), and an efficient pixel configuration can berealized. For example, it is possible to take a wide region effectivefor display of a pixel. By way of comparison, in the case where theregions at the left and right end portions (A1) are concealed by thelongitudinal BM 22B in FIG. 4A, there is a demerit that it is impossibleto take a wide region effective for display of the pixel and aninefficient pixel configuration is formed.

If the length L1 of the slit (Sa) is set to 0 in FIG. 4B, the one-sidecomb-like shape similar to the configuration β (FIG. 3) is obtained.Further, FIG. 4B shows the case where the opening portion 50A is notclosed for each pixel and is continuously opened over the pixel line inthe Y direction, but the opening portion 50A may be formed to have ashape closed for each pixel as described later. In any of theconfigurations, in terms of the shape of each pixel, the slit endportion A1 or the slit end SE occurs due to the existence of therectangular pixel electrode PIX or the like, and the difference incharacteristic occurs between regions positioned outside and inside it.

[Liquid Crystal Orientation]

The liquid crystal orientation of the liquid crystal layer 30 or thelike in the system of the present embodiment will be described withreference to FIG. 5 to FIG. 7.

FIG. 5 shows the configuration of the opening portion (slit) 50A in thesame manner as FIG. 4B. In this both-side comb-like shape, neighboringregions (F1, F2) of long sides (one side and the other side of the slitS opposed to each other in the width direction) of respective slits S inthe X direction are aligned approximately on the same X-directionallines. As rotation directions of liquid crystal molecules in the planeof the substrate (X, Y), there are two kinds of rotation directionsshown by F1 (solid line) and F2 (broken line) in the regions (F1, F2) ofthe long sides of the slit S. The regions having the same rotationdirection are aligned on the same X-directional line. In the Ydirection, two kinds of regions (F1, F2) are arranged alternately. Sinceliquid crystal rotation directions are identical in the rows adjacent inthe X direction and on the X-directional line, the orientation stabilityis high.

FIGS. 6A and 6B are a partially-enlarged views of FIG. 5 and show theregions (F1, F2) having two kinds of liquid crystal orientations. FIG.6A corresponds to a voltage-OFF time and an initial orientation state,and FIG. 6B corresponds to a voltage-ON time. A reference numeral 701denotes an image of a liquid crystal molecule. A reference sign F1denotes a region where a twist or a rotation direction of liquid crystalis a clockwise direction in an X-Y plane, and a reference sign F2denotes a region where the twist or the rotation direction is acounterclockwise direction. F1 and F2 denote neighboring regions aroundthe two opposed long sides (long sides of corresponding projectingportions) of the slit S (Sa, Sb). For example, a certain left-side slit55 (Sa) has an upper long side a1 and a lower long side a2. Also, aprojecting portion 53 (Ka) positioned on the right side of the slit55(Sa) has an upper long side a3 and a lower long side a4. The longsides a1 and a3 are arranged approximately on the same X-directionalline, and the long sides a2 and a4 are arranged approximately on thesame X-directional line.

A short side at one end of the slit S is opened and connected to alongitudinal slit 57 and each long side of the slit S has a cornerportion connected to the longitudinal slit 57. This corner portion hasan electric field control function (in other words, function ofstabilizing the liquid crystal orientation). More specifically, in along side (for example, a1) of each slit S, the rotation direction ofliquid crystal becomes the same (for example, F1) on a line extendingfrom a corner portion at one end closed by the electrode portion (58) toa corner portion at the other opening end, so that the orientation isstabilized. This holds true for the left and right slits S (Sa, Sb) withrespect to the communication opening portion 57 in the Y direction. Forexample, since the long side a3 of the slit Sb existing adjacent to thelong side a1 of the slit Sa similarly has an electric field controlfunction at the corner portion, the rotation direction of liquid crystalbecomes the same (F1) also in the long side a3, so that the orientationis stabilized. Further, in the long sides (a2, a4) on the other sides ofthe slits S, the regions (F2) having rotation direction opposite tothose of the long sides (a1, a3) on the one sides are formed, so thatthe orientation is stabilized.

In the state shown in FIG. 6A, respective liquid crystal molecules areoriented so that long axes thereof extend along the lateral (X)direction. The state is changed from the state shown in FIG. 6A to thestate shown in FIG. 6B by the voltage application to the upper and lowerelectrodes (31, 32). At this time, as illustrated in the drawings, bythe generated fringe electric field, the liquid crystal molecules standup in the Z direction while rotating in respective directions (clockwisedirection and counterclockwise direction) on the X-Y plane. The bothrotation directions exist in a mixed manner in a region of the slit Sbetween F1 and F2.

Also, in the state shown in FIG. 6B, orientation states of liquidcrystal molecules are approximately identical on the X-directional lineon the sides of each slit (for example, a1 to a4). Therefore, in thissystem, the response speed at the time of applying a voltage is fast(the response time is short), the orientation stability is high, and thedisplay quality becomes high.

FIGS. 7A and 7B show liquid crystal orientation states in the Zdirection in a cross section A-A′ in FIG. 5. FIG. 7A corresponds to avoltage-OFF time and an initial orientation state, and FIG. 7Bcorresponds to a voltage-ON time. In FIG. 7A, liquid crystal moleculesare initially oriented in a pre-tilt direction based on a predeterminedpre-tilt angle in the manner indicated by a reference numeral 800 by therubbing direction Rub (from left to right) on the array substrate 10.The liquid crystal molecules are oriented so that one end portions in along axis corresponding to an advancing direction of the rubbingdirection Rub (right side) rise slightly.

The orientation state is changed from the state shown in FIG. 7A to thestate shown in FIG. 7B by the voltage application. At this time, theliquid crystal molecules stand up in the Z direction as shown in FIG. 7while rotating in the plane (X, Y) as shown in FIG. 6. In FIG. 7B, aline “a” corresponds to the position of the communication openingportion 57 in a region above the slit S (Sa, Sb). On the right side(801) from the line “a”, liquid crystal molecules stand up in a positivedirection corresponding to the pre-tilt direction (800), and liquidcrystal molecules stand up in the opposite direction on the left side(802). More specifically, the liquid crystal molecules are less likelyto stand up on the left-side region (802) than on the right-side region(801), and the left-side region (802) is disadvantageous inresponsiveness.

In order to respond to this, as shown in FIG. 4B, this system adopts theconfiguration in which the lengths (L1, L2) of the left and right slits(Sa, Sb) are made different in the opening portion 50A and the ratio ofthe portion of L1 is reduced by setting the relation therebetween toL1<L2. In this manner, the characteristic of the responsiveness can beimproved.

[High-Speed Horizontal Electric Field Mode]

The high-speed horizontal electric field mode used in the liquid crystalpanel 1 of the present embodiment will be described with reference toFIGS. 4A and 4B and the like. For example, in the case of theconfiguration A, the common electrode COM is provided over a wholescreen across respective pixels in a planar shape, and a plurality ofrectangular openings (slits S) having a long side with a predeterminedlength and a short side with a predetermined width are provided atpositions facing the pixel electrodes PIX (FIG. 4B and the like). Theplurality of openings (S) are arranged so that extension directionsthereof are the same (in the X direction in FIG. 4B). In the presentembodiment, at the time of voltage application, liquid crystal moleculesin the liquid crystal layer 30 in the neighboring regions (F1 and F2 inFIG. 5 and FIG. 6) on one side and the other side of the long sidesfacing each other in the width direction (in the Y direction in FIG. 4B)of the opening (S) are oriented so as to be twisted by the rotations inthe directions opposite to each other. In this manner, thecharacteristic of the response speed is improved.

The length of the above-described opening (S) is, for example, 10 to 60μm, and it is preferably less than 40 μm. This is because the rotationdirection of the liquid crystal molecules is stabilized easily whensetting the length to less than 40 μm. The width of the above-describedopening (S) is, for example, 2 to 5 μm, and the pitch of the opening (S)is, for example, 4 to 10 μm. In order to enhance the response speed, thewidth and the pitch of the opening (S) are preferably smaller (thecharacteristics taking these into consideration will be described laterwith reference to FIG. 23 and the like).

A plurality of openings (S) arranged on the same line (longitudinal rowin FIG. 4B) are formed in the same shape so that positions of both endsare aligned with each other, and in the lines positioned adjacent toeach other, individual openings (S) are arranged so as to be shiftedfrom each other. The magnitude of the shift is ½ of the pitch in the Ydirection, for example, in FIG. 4B. With the alternate arrangement likethis (in other words, the approximately staggered arrangement), liquidcrystal molecules rotating in the same direction come close to eachother between the openings (S) of the adjacent lines as shown in FIG. 5and FIG. 6. The regions (F1, F2) having two kinds of rotation directions(right, left) are arranged approximately on the same lines,respectively. On the screen, lines of the regions (F1, F2) having twokinds of rotation directions are arranged alternately in the Ydirection. The orientation on the screen is stabilized by thisarrangement.

The above-described common electrode COM has the communication openingportion 57 which connects a plurality of openings (S) arranged adjacentto each other in a width direction on the same line (longitudinal row).The communication opening portion 57 connects a plurality of openings(S) arranged alternately on the adjacent lines so that short sides onrespective one ends are opened. Two long sides opposed in the widthdirection in one opening (S) have corner portions closed by theelectrode portion (58) at one ends and corner portions opened to thecommunication opening portion 57 at the other ends.

Two long sides opposed in the width direction in one opening (S) havetwo corner portions at intersection points with the communicationopening portion 57. These corner portions have a function as an electricfield control portion. The corner portion which is the electric fieldcontrol portion makes rotation directions of liquid crystal moleculesequal to each other and stabilizes the orientation in an extensiondirection of the long side of the opening (S) in the neighboring regionfrom the corner portion closed at the one end to the corner portionopened at the other end. As described above, in the opening portion 50having the comb-like shape with alternate teeth and provided with thecommunication opening portion 57, the corner portions serving as theelectric field control portions are provided at the individual openings(S), thereby improving the orientation stability.

Although the configuration in which the communication opening portion 57is not provided (for example, the configuration in which respectiveopenings (S) are independently formed in an island form or the like) ispossible, the manufacture is facilitated by providing the communicationopening portion 57. In the case where the configuration in which thecommunication opening portion 57 is not provided is adopted, it isdesirable to make the long side of the opening (S) relatively short inorder to improve the orientation stability (for example, 20 μm or less).

Alignment films (first and second alignment films) are subjected torubbing process of anti-parallel orientation in a directionapproximately parallel to an extension direction (X direction) ofrespective openings (S) so as to orient liquid crystal molecules in theliquid crystal layer 30 in a predetermined direction corresponding tothe above-described shapes of the electrode and the opening. Morespecifically, the rubbing process is performed so that the firstalignment film is rubbed in the above-described rubbing direction Ruband the second alignment film is rubbed in the direction oppositethereto.

In this manner, the liquid crystal in the liquid crystal layer 30 isoriented so that long axes of liquid crystal molecules on the opening(S) face approximately in the same direction (X) on respective longsides of the opening (S) opposed to each other in the width direction inan initial orientation state before the voltage application as shown inFIG. 6A. As shown in FIG. 6B, at the time of applying a voltage, liquidcrystal molecules in the neighboring regions (F1, F2) on one side andthe other side of the long sides of the opening (S) opposed to eachother in the width direction are rotated in the directions opposite toeach other to be oriented. In the neighboring region (F1) on the oneside of the long side of the opening (S), liquid crystal molecules arerotated in a clockwise direction to be oriented from the closed cornerportion to the opened corner portion, and in the neighboring region (F2)on the other side, liquid crystal molecules are rotated in acounterclockwise direction to be oriented from the closed corner portionto the opened corner portion. Regarding the Z direction, the liquidcrystal is correspondingly oriented so that long axes of liquid crystalmolecules stand up from the state of FIG. 7A to the state of FIG. 7B. Inthe intermediate region between the long sides of the opening (S)opposed to each other, liquid crystal molecules rotating in therespective directions (left and right) exist in a mixed manner. Asdescribed above, the orientation of liquid crystal molecules in theliquid crystal layer 30 on the electrode layer (including the openingportion 50) of the upper and lower electrodes (31, 32) is controlledseparately in the regions (F1, F2) of the respective rotation directions(left and right). Therefore, the response speed at the time of applyinga voltage becomes fast.

[Pixel and BM Configuration]

Next, FIG. 8 shows a configuration example of pixels (also referred toas cell), the BM 22 and the like in an X-Y plane in the liquid crystalpanel 1. Widths and the like of the BM 22 (22A, 22B) will be described.In the present embodiment, the BM 22 is composed of the lateral BMportion 22A extending in the X direction and the longitudinal BM portion22B extending in the Y direction.

A region of a pixel (also referred to as sub-pixel) formed by theintersection between a gate line 41 (GL) parallel to the X direction anda data line 42 (DL) parallel to the Y direction is constituted on thearray substrate 10 side. A reference numeral 901 denotes a schematicpixel region corresponding to a main pixel electrode PIX, in otherwords, a region of an opening of a pixel except for the BM 22 portion,and it has a longitudinally long rectangular shape in this case. FIG. 8shows a case of a three-color stripe arrangement of RGB as a pixelarrangement. The CF 23 is a layer for performing color separation oftransmitted light of the liquid crystal layer 30, and in this example,it is composed of layers 23 r, 23 g, and 23 b which are layers separatedinto the colors of R (red), G (green), and B (blue) for each pixel linein the Y direction in accordance with the pixel design. Note that, asother pixel arrangements, a delta arrangement, a diagonal arrangement, arectangle arrangement or the like is also possible. Further, the colorsare not limited to three colors of RGB, but the configuration of onecolor, two colors, four colors or the like can be adopted.

A TFT portion 43 is disposed at a position (in this example, in theupper left of pixel) near the intersection between the gate line 41 andthe data line 42. The TFT portion 43 includes a TFT element. The dataline 42 is connected to a source terminal, the gate line 41 is connectedto a gate terminal, and the pixel electrode PIX is connected to a drainterminal via a connection portion (referred to as contact receiver orthe like) 44. A portion of the pixel electrode PIX is connected on theconnection portion (contact receiver) 44 in an overlapping manner.

The BM 22 (22A, 22B) is disposed so as to conceal portions of the gateline 41, the data line 42, the TFT portion 43, and the like in a planview (X-Y) in an overlapping manner. The lateral BM portion 22A isdisposed on the gate line 41 and the TFT portion 43 in the X directionin an overlapping manner. The longitudinal BM portion 22B is disposed onthe data line 42 in the Y direction in an overlapping manner. Therefore,the width (h1) of the lateral BM portion 22A is larger than the width(h2) of the longitudinal BM portion 22B (h1>h2). Particularly, BM 22 isconfigured to have different widths (22A, 22B) as described abovebecause of the requirement of concealing the TFT portion 43 and therequirement of forming pixels (901) having the predetermined size,ratio, and the like.

In accordance with the configuration of the pixel and the BM 22described above, in this system, as shown in FIG. 3 and FIG. 4, theopening portion 50 is configured to have the lateral (X)-directionalslits S, and the upper and lower slit end portions in the Y direction(A1 in FIG. 4B and the like) of respective pixels are concealed by thelateral BM portion 22A having a larger width.

In the case of another pixel configuration, for example, in thestructure where the longitudinal BM portion 22B is wider than thelateral BM portion 22A, the configuration in which the opening portionis formed to have longitudinal (Y)-directional slits and left and rightslit end portions in the X direction of respective pixels are concealedby the longitudinal BM portion 22B can be correspondingly adopted.

[Configuration of Upper and Lower Electrodes]

FIG. 9 collectively shows the configuration examples regarding the upperand lower electrodes (31, 32). FIG. 9 shows a schematic shapecorresponding to three pixels of RGB. The rubbing direction Rub and theslit direction are the X direction. The first embodiment adopts theconfiguration A and the configuration α, and the second embodimentadopts the configuration B and the configuration (3.

In the configuration A, the upper electrode 31 (31A) is the commonelectrode COM and the lower electrode 32 (32A) is the pixel electrodePIX. The upper electrode 31A (COM) is basically formed to be a solidlayer over a whole surface region of a plurality of pixel regions and isprovided with openings (50A) for each pixel. The lower electrode 32A(PIX) is formed to have a rectangular shape for each pixel, and thelower electrodes 32A are regularly arranged in a grid-like shape. Aprojecting portion (1001) constituting a connection portion with thecontact receiver 44 is provided on an upper end side of the lowerelectrode 32A.

In the configuration B, the upper electrode 31 (31B) is the pixelelectrode PIX, and the lower electrode 32 (32B) is the common electrodeCOM. The upper electrode 31B (PIX) is basically formed to have arectangular shape and is provided with the slit (50B) for each pixel,and a connection portion (1001) with the contact receiver 44 is providedon an upper end side of the upper electrode 31B (PIX). The lowerelectrode 32B (COM) is formed to be a solid layer over a whole surfaceregion of a plurality of pixel regions, and is provided with aconduction hole (1002) for each pixel so as to correspond to theposition of the connection portion (1001).

Further, as the shape of the upper and lower electrodes (31, 32) and theslits (opening portions) 50, the configuration α adopts a both-sidecomb-like shape formed by the lateral (X)-directional slits S(particularly, trapezoid), and the configuration β adopts a one-sidecomb-like shape formed by the lateral (X)-directional slits S(particularly, rectangle). The configuration α (both-side comb-likeshape) is shown in FIG. 4, FIG. 10, and the like. The configuration β(one-side comb-like shape) is shown in FIG. 3, FIG. 16, and the like.

The present invention is not limited to the aspects described above butvarious combinations can be adopted. For example, the shape of theopening of the upper electrode 31A (COM) of the configuration A may bechanged to the one-side comb-like shape, and the shape of the upperelectrode 31B (PIX) of the configuration B may be changed to theboth-side comb-like shape. The shape of the comb tooth of theconfiguration α may be changed to a rectangle, and the shape of the combtooth of the configuration β may be changed to a trapezoid.

<First Embodiment>

Next, the liquid crystal display device 100 and the liquid crystal panel1 of the first embodiment will be described with reference to FIG. 10 toFIG. 15. The first embodiment adopts the configuration A (the upperelectrode 31A is the common electrode COM and the lower electrode 32A isthe pixel electrode PIX) and the configuration α (the both-sidecomb-like shape) as shown in FIG. 9.

[Configuration A, α-plane]

FIG. 10 shows a structure of pixels, BM 22 and the like in the liquidcrystal panel 1 (1A) of the first embodiment in an X-Y plane. FIG. 10shows a portion corresponding to three pixels of RGB. This is theconfiguration where the electrode shape of the configuration α (FIG. 12,and the like) is applied to the configuration shown in FIG. 8. Inparticular, this is the configuration where the slit end portions in theY direction of the opening portion 50A (at least a part thereof) areconcealed by the lateral BM portion 22A with a large width (h1) in eachpixel. The detail will be described in FIG. 12 and subsequent drawings.

The lower electrode 32A (the pixel electrode PIX) is connected to thecontact receiver 44 at the projecting portion 1101 on an upper end sidethereof. The opening portion 50A formed by the lower electrode 32A (PIX)and the upper electrode 31A (COM) has a both-side comb-like shape andschematically corresponds to that obtained by changing the rectangleshown in FIG. 4B to trapezoid. A plurality of lateral (X)-directionaltrapezoidal slits S formed by the upper electrode 31A (COM) are providedabove a rectangular surface of the lower electrode 32A (PIX). A portionof a plane where the upper electrode 31A (COM) does not overlap thelower electrode 32A (PIX) constitutes the opening portion 50A.

In this system, the lateral BM portion 22A extending in a directionparallel to the direction (X) of the slits S of the opening portion 50Ais larger in width than the longitudinal BM portion 22B extending in adirection perpendicular thereto (h1>h2). In other words, the directionof the slits S of the opening portion 50 is designed so as to conformwith the direction (X) of the lateral BM portion 22A with a larger width(h1). Also, the slit end portions (A1, A2 in FIG. 12) of the openingportion (slits) 50A of each pixel are concealed by the lateral BMportion 22A with a larger width (h1). Accordingly, the secondcharacteristic of the pixel end portion region Q2 as described above(FIG. 4B) is suppressed and the overall characteristics can beuniformized to the first characteristic of the pixel-inside region Q1.Note that the extension direction of the lateral BM portion 22A withrespect to the X-directional slits S is not necessarily limited to thesame direction, but it may be made oblique to a certain extent. Forexample, the direction may be made to conform with the inclination ofthe trapezoid of the slits S or the comb teeth.

[Configuration A—Cross Section]

FIG. 11 shows an X-Z cross-sectional structure of pixels, BM 22, and thelike of the liquid crystal panel 1 (1A) of the first embodiment. FIG. 11corresponds to an A-A′ cross section in FIG. 10. The array substrate 10is made up of, for example, the gate line 41 (not shown), the data line42 (1201), the TFT portion 43, the lower electrode 32A (PIX), thedielectric film 33 and the upper electrode 31A (COM) formed on the glasssubstrate 11 in this order from below and other insulating films 12. Alayer for the lower electrode 32A (PIX) is formed on a layer planarizedby the insulating film 12, and a layer for the upper electrode 31A (COM)is formed on the planarized dielectric film 33. A surface of the commonelectrode COM and a surface of the pixel electrode PIX are opposed inparallel with each other via the dielectric film 33.

The TFT portion 43 is composed of a TFT element including a gateelectrode, a gate insulating film, a semiconductor film, andsource/drain electrodes. A reference numeral 1201 denotes a data line 42connected to a terminal of the TFT portion 43 or a line of the pixelelectrode PIX connected thereto. A reference numeral 1202 denotes aconduction portion of the upper and lower layers (1201, 32A) in the Zdirection. Note that the TFT element may be of a bottom gate type or ofa top gate type. The semiconductor film may be made of any of amorphoussilicon, oxide semiconductor, and organic semiconductor.

[Light-Shielding Configuration Example (1)]

FIG. 12 shows a first light-shielding configuration example by thelateral BM portion 22A corresponding to only one pixel in FIG. 10. Inthe slits (opening portion) 50A of a pixel, regions A1 and A2corresponding to the Y-directional upper and lower slit end portions areprovided. A reference sign SE denotes a slit end. In the firstlight-shielding configuration example, a region including an upper-sideprojecting portion 1101 positioned on the upper side of the SE line ofthe upper-side slit end portion A1 is concealed by the lateral BMportion 22A. A lower-side slit end portion A2 positioned on the lowerside of another SE line is similarly concealed by the lateral BM portion22A. The width h1 of the lateral BM portion 22A is particularly definedas h1 a. A corresponding effect can be obtained even in theconfiguration where only one end portion of the upper and lower slit endportions in the Y direction is concealed.

The projecting portions which are individual comb teeth and theindividual slits S have a trapezoidal shape. Reference signs K1 and K2denote upper left and right outermost comb teeth in the Y direction. Inthe trapezoid of the comb teeth, a short upper side is provided on theinner side of the pixel, and a long lower side is provided on the outerside of the pixel. A reference sign Sa1 denotes a left-side outermostslit (except for Sw) on an upper side in the Y direction, and areference sign Sb1 denotes a right-side outermost slit (except for Sw).The reference sign Sw denotes an outermost large slit on an upper sidein the Y direction of the opening portion 50 (in other words, a largeslit positioned outside the comb teeth K1 and K2). Slits Sa1 and Sb1 andthose positioned below them have the same shape. In the trapezoid of theslit S, a long lower side is provided on the inner side of the pixel,and a short upper side is provided on the outer side of the pixel.

The width h1 (h1 a) of the lateral BM portion 22A is made to be equal toor more than a width (width H described later) of a predetermineddistance ranging from the slit end SE of the pixel to the outside. Morespecifically, the width h1 of the lateral BM portion 22A has a sizecapable of concealing the gate line 41 and the TFT portion 44 and alsoconcealing at least a region of the width (H) of the predetermineddistance ranging from the slit end SE to the outside. A configurationwhere the width h1 is made larger (FIG. 13 and subsequent drawings) canalso be adopted. Since the slit end portion A1 and the like arecorrespondingly concealed, the aperture ratio of the pixel is slightlyreduced, but the influence of the second characteristic of the pixel endportion region Q2 can be reduced, and uniformity of the characteristicof the pixel can be improved.

[Light-Shielding Configuration Example (2)]

FIG. 13 shows a second light-shielding configuration example. In thisconfiguration, the width h1 of the lateral BM portion 22A is made larger(h1 b) than that in the configuration shown in FIG. 12, and the slit endportions A1 and the like are more concealed. The width h1 b (lower side)of the lateral BM portion 22A reaches a little inner position from theupper-side slit end SE (a3 in FIG. 15). This position is near theoutermost slit Sw (slightly outside the right-side outermost comb toothK1). Similarly, for the lower-side slit end portion A2, a region rangingfrom the slit end SE to a predetermined slightly inner position isconcealed.

[Light-Shielding Configuration Example (3)]

FIG. 14 shows a third light-shielding configuration example. In thisconfiguration, the width h1 of the lateral BM portion 22A is furthermade larger (h1 c), and the slit end portions A1 and the like are stillmore concealed. The width h1 c (lower side) of the lateral BM portion22A reaches an inner position from the upper-side slit end SE (a4 inFIG. 15). This position is near the center line of the right-sideoutermost comb tooth K1 (slightly outside the left-side outermost combtooth K2). Similarly, for the lower-side slit end portion A2, a regionranging from the slit end SE to a predetermined inner position isconcealed.

Note that the configuration where the outermost opening (Sw) portion ismade small by moving the Y-directional position of the comb tooth(projecting portion) may be adopted.

[Complement]

FIG. 15 shows complement regarding the configuration examples of theslit end SE and the light-shielding structure in the case of theabove-described opening portion 50A. A reference sign A1 denotes aregion of a slit end portion including a slit end SE in its center. Areference sign A3 denotes a region near the outermost slit Sw. An effectof hiding the second characteristic of the pixel end portion region Q2(the response speed, the luminance curve, the orientation stability, andthe like) can be obtained by concealing at least a region ranging in apredetermined width H (a2) from the slit end SE (a1) by the BM 22. Sincethe lateral BM portion 22A as shown in FIG. 8 exists, the width h1 ofthe lateral BM portion 22A is set to the width h1 a including the widthH and the like in accordance with that. In this manner, In this manner,an efficient pixel configuration including the BM 22 can be achieved,and the characteristics of the pixel can be uniformized and improved.

<Second Embodiment>

Next, a liquid crystal display device 100 and a liquid crystal panel 1of the second embodiment will be described with reference to FIG. 16 toFIG. 19. The second embodiment adopts the configuration B (the upperelectrode 31B is the pixel electrode PIX and the lower electrode 32B isthe common electrode COM) and the configuration β (the one-sidecomb-like shape) as shown in FIG. 9.

[Configurations B, β-plane]

FIG. 16 shows a structure of pixels, BM 22, and the like of the liquidcrystal panel 1 (1B) of the second embodiment in an X-Y plane. FIG. 16shows a portion corresponding to three pixels of RGB. This is theconfiguration where an electrode shape (FIG. 18, and the like) of theconfiguration β is applied to the configuration shown in FIG. 8. Inparticular, this is the configuration where the slit end portions in theY direction of the opening portion 50B (at least a part thereof) areconcealed by the lateral BM portion 22A with a large width (h1) in eachpixel.

The lower electrode 32B (COM) is an electrode composed of a solid layerover a whole surface. The upper electrode 31B (PIX) is basically formedto have a rectangular shape for each pixel and is provided withrectangular slits S on its left side. A plurality of slits S formed by aplurality of rectangular projecting portions (comb teeth) in the lateral(X) direction of the upper electrode 31B (PIX) are provided above asurface of the lower electrode 32B (COM). The upper electrode 31B (PIX)is connected to the contact receiver 44 extending from the TFT portion43 at a portion (connection portion 1001) on an upper side thereof. Aportion of a plane where the upper electrode 31B (PIX) does not overlapthe lower electrode 32B (COM) constitutes the opening portion 50B.

In this system, like the case of FIG. 10 (first embodiment), the slitend portions (A1, A2 in FIG. 18) in the Y direction of the openingportion (slits) 50B are concealed by the lateral BM portion 22A with alarge width (h1) in each pixel. Accordingly, the second characteristicof the pixel end portion region R2 as described above (FIG. 3B) issuppressed and the overall characteristics can be uniformized to thefirst characteristic of the pixel-inside region R1.

[Configuration B—Cross Section]

FIG. 17 shows an X-Z cross-sectional structure of pixels, BM 22, and thelike of the liquid crystal panel 1 (1B) of the second embodiment. FIG.17 corresponds to a B-B′ cross section in FIG. 16. The array substrate10 is made up of, for example, the gate line 41 (not shown), the dataline 42 (1801), the TFT portion 43 (not shown), the lower electrode 32B(COM), the dielectric film 33 and the upper electrode 31B (PIX) formedon the glass substrate 11 in this order from below and other insulatingfilms 12. A layer for the lower electrode 32B (COM) is formed on a layerplanarized by the insulating film 12, and a layer for the upperelectrode 31B (PIX) is formed on the planarized dielectric film 33.

A reference numeral 1801 denotes a data line 42 connected to a terminalof the TFT portion 43 and a line of the pixel electrode PIX connectedthereto. A reference numeral 1802 denotes a conduction portion of theupper and lower layers (1801, 31B) in the Z direction. A referencenumeral 1803 denotes a portion of a conduction hole (1002) provided inthe lower electrode 32B (COM).

[Light-Shielding Configuration Example]

FIG. 18 shows a light-shielding configuration example by the lateral BMportion 22A corresponding to only one pixel in FIG. 16. The shape of thepixel electrode PIX and the like are similar to those shown in FIG. 3B.In the slits (opening portion) 50B of a pixel, regions A1 and A2corresponding to the Y-directional upper and lower slit end portions areprovided. A reference sign SE denotes a line of a slit end. In thislight-shielding configuration example, a region including the projectingportion Ew described above on the upper side of the SE line of theupper-side slit end portion A1 is concealed by the lateral BM portion22A. Similarly, for the lower-side slit end portion A2, a region on thelower side of the SE line is concealed by the lateral BM portion 22A.The width h1 of the lateral BM portion 22A is particularly defined as h1d. A corresponding effect can be obtained even in the configurationwhere only one end portion of the upper and lower slit end portions inthe Y direction is concealed.

[Complement]

FIG. 19 shows complement regarding the configuration examples of theslit end SE and the light-shielding structure in the case of theabove-described opening portion 50B. This complement has the contentscorresponding to the case shown in FIG. 3. A reference sign Ew denotes awide projecting portion at an upper end portion of the pixel electrodePIX, and this portion has a connection portion 1001. A reference sign E1denotes a projecting portion which is an outermost comb tooth (exceptfor Ew) in the Y direction. A reference sign S1 denotes an outermostslit in the Y direction. A reference sign a0 denotes a side of an endportion of the pixel electrode PIX. A reference sign a1 denotes a slitend SE. An effect of hiding the second characteristic of the pixel endportion region R2 (the response speed, the luminance curve, theorientation stability, and the like) can be obtained by concealing atleast a region ranging in a predetermined width H (a2) from the slit endSE (a1) by the BM 22. Since the lateral BM portion 22A as shown in FIG.8 exists, the width of the lateral BM portion 22A is set to the width h1d including the width H in accordance with that. In this manner, anefficient pixel configuration including the BM 22 can be achieved, andthe characteristics of the pixel can be uniformized and improved. Inaddition, a configuration where the width (h1) of the light shielding ismade larger can be adopted like the case of the first embodiment.

[Characteristics]

Next, characteristics, conditions, specific values, and the like for thedesign of a preferred pixel (cell) in the system of the liquid crystaldisplay device 100 of the above-described embodiment will be describedwith reference to FIG. 20 to FIG. 30. Note that representativecharacteristics are collectively shown in FIG. 30. The description willbe made for the case of the first embodiment, but it can be similarlyapplied to the second embodiment.

[Characteristic (1)—Light-Shielding Width]

The characteristic of the width (h1) of the above-described BM 22 (thelateral BM portion 22A) for concealing the region around the slit endportions of the pixel will be described with reference to FIG. 20 toFIG. 22. As the condition of the above-described minimum light-shieldingwidth H (the predetermined distance from the slit end SE to theoutside), H ≥ cell thickness d×5/3 μm and h1>H are established.

FIG. 20 shows a pixel configuration example (defined as configuration C)to be a model for simulating/calculating the light-shielding conditions.In the configuration C, the upper electrode is the common electrode COM,the lower electrode is the pixel electrode PIX, the one-side comb-likeshape is adopted, and the slit and comb tooth have a trapezoidal shape.A reference numeral 2100 denotes a schematic pixel region, a referencenumeral 2101 denotes an electrode portion (COM), a reference numeral2102 denotes a rectangle of the pixel electrode PIX on the back faceside, and a reference numeral 50C denotes an opening portion (slits). Areference sign y1 denotes a pixel end portion in the Y direction (endportion of an opening of the opening portion 50C) and a reference signy2 denotes a side of the pixel electrode PIX, namely, a linecorresponding to the above-described slit end SE. Note that theconditions for the configurations A and B and the like can be easilydeveloped based on the simulation calculation result of thisconfiguration C.

FIG. 21 shows the result obtained by calculating an in-plane luminancedistribution based on the model (configuration C) shown in FIG. 20. Awhite color indicates that the luminance is high. As illustrated, in aregion 2201 (corresponding to R1, Q1 described above) on an inner sidefrom the slit end portion (y2), laterally elongated regions with theluminance (white) corresponding to respective slits S are longitudinallyarranged orderly, the uniformity thereof is high and the distortion ondisplay does not occur. On the other hand, in a region 2202(corresponding to the R2, Q2 described above) on an outer side from theslit end portion (y2), the characteristic is different from that of theregion 2201, and the uniformity is low.

FIG. 22 shows a brightness distribution in C-C′ cross section in FIG.21. The brightness is shown by the shape of a distribution oftransmittance in accordance with the Y-directional position. Asillustrated, in a range 2301 positioned inside the slit end portion(y2), the distribution of an approximately uniform brightness(transmittance) can be obtained. In a range 2302 positioned outside y2,the brightness (transmittance) is degraded. Therefore, a configurationwhere the range 2302 positioned outside y2 is also concealed by the BM22 is adopted. Furthermore, since the degradation or fluctuation of thebrightness appears in the range 2303 from y3 to y2, the configurationwhere the range 2303 is also concealed by the BM 22 may be adopted.

Based on the results described above, it is desirable that a portionranging in a certain distance from the slit end SE in the Y direction ofthe pixel is concealed by the BM 22. This distance is defined as thewidth H. The width h1 of the lateral BM portion 22A is set to be largerthan the width H (h1>H). The cell thickness is defined as d (FIG. 27).The region in which the brightness spreads (region outside y2) isproportional to the cell thickness d. It is desirable that the width His set to d×5/3 μm or more from the slit end SE. For example, in thecase where d is 3.0 μm, H≥d×5/3 μm=5 μm is obtained.

[Characteristic (2)—Slit Pitch]

The characteristic of the pitch (p) of the slit S in the shapes of theupper and lower electrodes (31, 32) or the like will be described withreference to FIG. 23 and FIG. 24. FIG. 23 shows the opening portion 50Aof configurations A and a in a partially-enlarged manner. First, thetotal slit length L0 in the X direction is, for example, 10 to 60 μm, inparticular, less than 40 μm, preferably, 20 μm. In the case where L0 ismade short, the orientation stability of liquid crystal becomes high. Onthe contrary, in the case where L0 is made long, the luminance becomeshigh. Regarding slit lengths L1 and L2 of left and right slits S (Sa,Sb), L1<L2 is preferable in conformity with the rubbing direction Rub asdescribed above (L1=L2 in FIG. 23). The width of a short side of theslit S (p−w2) is set to, for example, 2 to 5 μm, and the response speedbecomes high as the width becomes short.

A reference sign p denotes a Y-directional pitch of a plurality of slitsS. A reference sign W denotes an X-directional width of a longitudinalslit (communication opening portion) 57. A reference sign D 1 denotes anX-directional width of a longitudinal electrode portion (58). Areference sign w1 denotes an upper-side width of trapezoids of combteeth (projecting portions) ka and kb, and a reference sign w2 denotes alower-side width thereof. A reference sign x0 denotes an X-directionalposition of an upper side on the one closed end side of the slit S, alower side of the comb tooth, and both sides of the electrode portion(58), and a reference sign x1 denotes an X-directional position of alower side on the other opened end side of the slit S, an upper side ofthe comb tooth, and both sides of the communication opening portion 57.A reference sign θ denotes an angle formed between the X direction andan oblique side of a trapezoid of the comb teeth (Ka, Kb), and itcorresponds to an angle of an oblique side of the slit S.

FIG. 24 shows a graph of a response speed characteristic of thesimulation result regarding the slit pitch (p). FIG. 24 shows a responsetime (T) with respect to the pitch (p). A point (ton25) of a rhombus (♦)denotes a response time (second) at a voltage ON time (OFF state → ONstate) at a temperature of 25° C., and a point (ton0) of a triangle (A)denotes a response time (second) at a voltage ON time (OFF state → ONstate) at a temperature of 0° C. FSS=1 means that a response time of aconventional FFS system is assumed to 1. From this result, it isunderstood that when slit pitch (p) becomes longer, the response speedbecomes slow. Therefore, as a condition of improving the responsivenesscompared with the conventional FFS system, p<9 μm is obtained.

[Characteristic (3)—Angle of Comb Tooth]

The characteristics of the angle θ of a comb tooth (trapezoid) in theshape shown in FIG. 23 or the like will be described with reference toFIG. 25. FIG. 25 shows a table of the result of the simulation regardingthe shape of a comb tooth. The orientation stability is determined withthe respective combinations of the slit length L2 of the right-side slitSb and the angle θ. Note that, as the orientation stability, the quality(uniformity) of the luminance distribution on display (planar view) isdetermined. Double circle denotes a stable state, x denotes an unstablestate, and triangle (Δ) denotes a fluctuating state between the stablestate and the unstable state. From this experimental result, it has beenunderstood that there is a relationship between the angle θ and theorientation stability. More specifically, the characteristics of theorientation shown in FIG. 5, FIG. 6, and the like (characteristic thatrotation directions of liquid crystal molecules coincide with each otheron a line and the like) are influenced by the angle θ. The condition ofthe angle θ is set to θ>0.5° based on the result of the stable state(double circle).

Even in the case where the rubbing direction (Rub) slightly deviatesfrom the X direction (0°) due to a manufacturing error of the liquidcrystal panel 1, the deviation can be allowed by the inclination (angleθ) of the trapezoid of the comb tooth, so that the orientation stabilitycan be maintained.

[Characteristic (4)—Longitudinal Slit Width]

The characteristic of the width W of the longitudinal slit(communication opening portion) 57 in the shape shown in FIG. 23 or thelike will be described with reference to FIG. 26. FIG. 26 shows a graphof the simulation result (brightness near the longitudinal slit 57)regarding the width W of the longitudinal slit 57. This is a graphcorresponding to the distribution shown in FIG. 21 and the A-A′ line inFIG. 23. A line of x1 corresponds to the line of the end portions of theleft-side slit (Sa) and the comb tooth (Kb) on the opened side shown inFIG. 23. A reference numeral 2701 denotes a region of a comb tooth (Kb)positioned on the left side of x1, and a reference numeral 2702 denotesa region of the longitudinal slit 57 (width W) positioned on the rightside of x1. The brightness (transmittance) in the region 2702 comesclose to 0 (black) from around the line x1. For example, the brightnessbecomes almost zero at the position of 3.5 μm or more from x1 to theright. Therefore, a shorter width W is preferable. From this result, thecondition of the width W of the longitudinal slit 57 is, for example,W≤7 μm, and particularly, W≤4 μm is preferable.

Note that the configuration in which the width W of the longitudinalslit 57 satisfies W≤0 can also be adopted. More specifically, in thecase of W=0, distal ends of a plurality of comb teeth (projectingportions) align in the Y direction in the opening portion 50A, and thedistal ends are separated from each other via clearances in the Ydirection and a plurality of slits S are opened to communicate with eachother. Further, in the case of W<0, distal ends of a plurality ofrespective comb teeth (projecting portions) enter adjacent slits S inthe X direction, in other words, they enter the adjacent slits in astaggered manner.

[Characteristic (5)—Retardation]

The characteristic of And (retardation R=Δn×d) in the liquid crystallayer 30 will be described with reference to FIGS. 27A, 27B and 28. FIG.27A shows a cell thickness d and a refractive index difference Δnregarding the retardation R (Δnd), and FIG. 27B shows a relationshipbetween the cell thickness d and the retardation R (Δnd).

The retardation R (Δnd) represents a phase difference when light goesthrough the liquid crystal layer 30 having birefringence (also referredto as refractive index anisotropy). R=Δn×d is defined. The intensity oftransmitted light becomes maximum at R (Δnd)=mλ (m: integer number, λ:light wavelength). A reference sign d denotes the cell thickness, and itis a length of the liquid crystal layer 30 in the Z direction as shownin FIG. 27A. A reference sign Δn denotes a refractive index differenceof liquid crystal in the liquid crystal layer 30, and Δn=(ne−no). As therefractive indexes (ne, no) of nematic liquid crystal, ne is arefractive index of abnormal light (refractive index parallel to adirection of a long axis of a liquid crystal molecule) and no is arefractive index of ordinary light (refractive index perpendicular to adirection of a long axis of a liquid crystal molecule).

In this system, an optimal R (Δnd) varies in accordance with the cellthickness d unlike other many liquid crystal modes. This relationship isshown by a function: y=0.11x in the case where the cell thickness d isrepresented as x and R (Δnd) is represented as y.

FIG. 28 shows a graph of brightness (transmittance) in accordance with R(Δnd) as the simulation result. A point of square (▪) shows the case ofd=2.9 μm, and a point of a rhombus (♦) shows the case of d=2.5 μm. Forexample, R (Δnd) darker than the maximum transmittance is adopted inaccordance with a color (CF23) of a pixel. In view of this, an R (Δnd)value equal to or more than A line where the brightness (luminance) isabout 80% or higher is adopted in this system. More specifically, apreferable condition of R (Δnd) is R (Δnd)≥0.11×d. For example, in thecase of d=2.5 μm, R≥0.275 μm, and in the case of d=2.9 μm, R≥0.319 μm.An of liquid crystal in the liquid crystal layer 30 and the cellthickness d are determined in accordance with the condition of R.

[Characteristic (6)—Elastic Constant]

The characteristic of elasticity of liquid crystal in the liquid crystallayer 30 of this system will be described with reference to FIG. 29.FIG. 29 shows a graph of a relationship between a time and brightness inaccordance with the elastic constant of liquid crystal (particularly,K22) as a simulation result. As the elastic constant K of liquid crystalmolecules (nematic liquid crystal) in the liquid crystal layer 30 ofthis system, particularly, the twist elastic constant: K22 is adopted.K22 corresponds to an elastic constant when liquid crystal moleculesrotate (twist) within an X-Y plane.

FIG. 29 shows a graph of a relationship of brightness to a time(millisecond) in accordance with values of respective elastic constantsK22. The time is a response time required for the change of brightness(transmittance) at the time of voltage OFF→voltage ON, in other words, atime required for the rotation of liquid crystal molecules. Thebrightness is standardized on the assumption that the maximum valueis 1. A reference numeral 3001 denotes a curve group in the case ofelastic constant K22>7.2. A reference numeral 3002 denotes a curve inthe case of K22=7.2.

In this system, the high response speed is realized by activelyutilizing elastic energy of liquid crystal. Particularly, rotation ofliquid crystal within an X-Y plane is utilized as shown in FIG. 5, FIG.6, and the like. Therefore, the elastic constant K (particularly, K22)should be large as much as possible in this system. In the case wherethe elastic constant K22 is excessively small, undesirable behavioroccurs. For example, in the case of K22=7.2 as shown by the referencenumeral 3002, it is understood that the response speed is slow.Therefore, in this system, K22>7.2 is adopted as a preferred conditionof the elastic constant K22 from FIG. 29.

Effects and the Like

As described above, according to the liquid crystal display devices 100of the respective embodiments, it is possible to provide the liquidcrystal display device 100 of a new system (high-speed horizontalelectric field mode) which can improve the response speed, the displayquality, and the like as compared with the conventional FFS system orthe like in addition to the wide viewing angle and the high apertureratio. The response speed, the brightness, the orientation stability inpixels can be improved, and the display quality can be improved byuniformizing the pixel characteristics.

In the foregoing, the invention made by the inventor of the presentinvention has been concretely described based on the embodiments.However, it is needless to say that the present invention is not limitedto the foregoing embodiments and various modifications and alterationscan be made within the scope of the present invention. For example,regarding the shape of the opening portion 50 formed by the upper andlower electrodes (31, 32) and the like, various modified shapesdescribed below can be adopted.

(1) Various shapes such as a rectangle, a trapezoid and a triangle maybe adopted as the shapes of the slit S and the comb tooth. For example,a triangle may be adopted by setting the width w1 of an upper side ofthe comb tooth to 0 in FIG. 23.

(2) In the configuration α, the arrangement of the left and right slitsS and comb teeth is not limited to the alternate arrangement, but anarrangement where the Y-directional positions thereof are aligned can beadopted. The shift length in the alternate arrangement is not limited to½ of the slit pitch (p). Further, not only the X-directional lengths ofthe left and right slits S and comb teeth with respect to theY-directional slit (57) and electrode portion (58), but also theY-directional widths and pitches thereof may be changed.

(3) In the case where the X direction (for example, the extensiondirections of the gate line 41 and the lateral BM portion 22A) isdefined as 0°, the direction of the slits S of the opening portion 50may be slightly inclined by a certain angle (for example, 5°). Also, twoor more kinds of angles may be provided as this angle and they may becaused to exist in a mixed manner in a pixel.

(4) The shape of the light-shielding lateral BM portion 22A may bechanged in accordance with the shapes of the slits S and the comb teeth.For example, the width (h1) may be changed for respective pixels insteadof a simple linear shape with a constant width. For example, the width(h1) may be changed in conformity with the Y-directional positions ofrectangles and trapezoids of the slits S and the comb teeth of thepixels. For example, the width (side) of the lateral BM portion 22A maybe changed to form a shape which coincides with an oblique side of thetrapezoid of the comb tooth. Further, for example, two kinds of widths(h1) may be provided in conformity with the Y-directional positions ofleft and right outermost comb teeth of a pixel in the configuration α.For example, the configuration in which a width up to the position a3 isset for the right-side slit portion and a width up to the position a4 isset for the left-side slit portion in FIG. 15 may be adopted.

The present invention can be utilized for a liquid crystal displaydevice including a liquid crystal touch panel and the like.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A display device comprising: afirst substrate; a liquid crystal layer arranged on the first substrate;a plurality of pixels arranged on the first substrate, the pixelscomprising: a first pixel; and a second pixel adjacent to the firstpixel in a first direction; a common electrode arranged between thefirst substrate and the liquid crystal layer, the common electrodecomprising: a first base portion extending in a second directioncrossing the first direction and arranged in the first pixel; a secondbase portion extending in the second direction and arranged in thesecond pixel; a third base portion extending in the second direction andarranged between the first pixel and the second pixel; a firstconnecting portion extending in the first direction, the firstconnecting portion coupling the first base portion to the third baseportion and the second base portion; a first projecting portionextending from the third base portion in a direction from the third baseportion to the first base portion, the first projecting portion beingseparated from the first base portion; a second projecting portionextending from the third base portion in a direction from the third baseportion to the first base portion, the second projecting portion beingseparated from the first base portion; a third projecting portionextending from the first base portion in a direction from the first baseportion to the third base portion, the third projecting portion beingseparated from the third base portion, the third projecting portionbeing arranged between the first projecting portion and the secondprojecting portion in the second direction; and a fourth projectingportion extending from the third base portion in a direction from thethird base portion to the second base portion, the fourth projectingportion being separated from the second base portion; a first pixelelectrode arranged between the first substrate and the liquid crystallayer in the first pixel, the first pixel electrode overlapping thefirst projecting portion, the second projecting portion and the thirdprojecting portion in a plane view; and a light shielding layeroverlapping the first connecting portion in the plane view.
 2. Thedisplay device according to claim 1, wherein the fourth projectingportion is arranged between the first projecting portion and the secondprojecting portion in the second direction.
 3. The display deviceaccording to claim 1, wherein the common electrode further comprises: asecond connecting portion extending in the first direction, the secondconnecting portion coupling the first base portion to the third baseportion and the second base portion, and wherein the first projectingportion, the second projecting portion, and the third projecting portionare arranged between the first connecting portion and the secondconnecting portion in the second direction.
 4. The display deviceaccording to claim 1, wherein the first pixel electrode comprises: afirst portion formed into a rectangle shape; and a second portionextending from the first portion in a direction from the firstprojecting portion to the first connecting portion.
 5. The displaydevice according to claim 4, wherein a length of the second portion ofthe first pixel electrode is smaller than a length of the first portionof the first pixel electrode in the first direction and the seconddirection.
 6. The display device according to claim 4, wherein the firstportion of the first pixel electrode overlaps the first projectingportion, the second projecting portion and the third projecting portionin the plane view.
 7. The display device according to claim 4, furthercomprising: a first switch coupled to the second portion of the firstpixel electrode.
 8. The display device according to claim 4, wherein thelight shielding layer overlaps the second portion of the first pixelelectrode in the plane view.
 9. The display device according to claim 1,wherein the first projecting portion comprises: a first side extendingwith a first angle with respect to the first direction; and a secondside extending with a second angle different from the first angle withrespect to the first direction.
 10. The display device according toclaim 9, wherein the first side of the first projecting portion iscloser to the first connecting portion than the second side of the firstprojecting portion, and wherein the light shielding layer overlaps thefirst side of the first projecting portion, but does not overlap thesecond side of the first projecting portion.
 11. The display deviceaccording to claim 1, wherein the first projecting portion has: a firstwidth in a first area in the second direction; and a second width largerthan the first width in a second area closer to the third base portionthan the first area in the second direction.
 12. The display deviceaccording to claim 1, wherein the first projecting portion is theclosest to the first connecting portion compared with the secondprojecting portion and the third projecting portion.
 13. The displaydevice according to claim 12, wherein the light shielding layer overlapsthe first connecting portion and an area between the first connectingportion and the first projecting portion in the plane view.
 14. Thedisplay device according to claim 12, wherein the light shielding layeroverlaps the first connecting portion and the first projecting portionin the plane view.
 15. The display device according to claim 12, whereinthe light shielding layer overlaps the first connecting portion and anarea between the first connecting portion and the second projectingportion in the plane view.
 16. The display device according to claim 1,wherein the first pixel electrode is arranged between the commonelectrode and the first substrate.
 17. The display device according toclaim 1, further comprising: a second substrate opposed to the firstsubstrate, wherein the light shielding layer is arranged on the secondsubstrate.